This invention relates to compositions, to inks and to dyes and to their use in ink jet printing (xe2x80x9cIJPxe2x80x9d).
IJP is a non-impact printing technique in which droplets of ink are ejected through a fine nozzle onto a substrate without bringing the nozzle into contact with the substrate.
There are many demanding performance requirements for dyes in inks used in IJP. For example they desirably provide sharp, non-feathered images having good water-fastness, light-fastness and optical density. The inks are often required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust over the tip of an ink jet nozzle because this will stop the printer from working. The inks should also be stable to storage over time without decomposing or forming a precipitate which could block the fine nozzle.
According to the first aspect of the present invention there is provided a compound of the Formula (1) and salts thereof: 
wherein:
each A independently is N, Cxe2x80x94Cl, Cxe2x80x94CN or Cxe2x80x94NO2,
each Ar independently is a substituted aryl group carrying a xe2x80x94COOH group ortho to the azo (xe2x80x94Nxe2x95x90Nxe2x80x94) group;
L is an aliphatic group carrying a xe2x80x94COOH, xe2x80x94SO3H or xe2x80x94PO3H2 group;
each Z independently is xe2x80x94SR2, xe2x80x94OR3, xe2x80x94NR4R5 or a labile atom or group;
each X independently is xe2x80x94Sxe2x80x94, xe2x80x94Oxe2x80x94 or xe2x80x94NR1xe2x80x94;
each R1 independently is H or optionally substituted alkyl; and
R2, R3, R4 and R5 are each independently H, optionally substituted alkyl, optionally substituted aryl or optionally substituted aralkyl; or
R4 and R5 together with the nitrogen to which they are attached form an optionally substituted five or six membered ring.
Preferably each A is N.
Preferably the aryl groups represented by Ar contain up to 12 carbon atoms, more preferably up to 10 carbon atoms and optionally contain one or more hetero atoms selected from O, S and N. The aryl groups optionally carry one or more substituents in addition to the xe2x80x94COOH group ortho to the azo group in Formula (1).
Suitable aryl groups containing one or more hetero atoms include pyridyl, pyrazolyl, thienyl or indanyl. It is preferred however that the aryl groups are free from hetero atoms, for example phenyl or naphthyl.
More preferably each Ar independently is optionally substituted 1-carboxy-naphth-2-yl or optionally substituted 2-carboxy phenyl. It is especially preferred that each Ar independently is of the Formula (2) or (3): 
wherein:
each B independently is xe2x80x94OH, xe2x80x94SO3H, xe2x80x94PO3H2, xe2x80x94COOH, xe2x80x94CF3, optionally substituted alkyl, optionally substituted alkoxy, optionally substituted amino, halo, xe2x80x94NO2, xe2x80x94CN or xe2x80x94SO2T;
T is optionally substituted alkyl (preferably optionally substituted C1-10-alkyl) optionally substituted aryl (preferably optionally substituted phenyl), xe2x80x94NR6R7, vinyl or a group convertible to vinyl on treatment with aqueous alkali;
R6 and R7 are each, independently, H, optionally substituted alkyl or optionally substituted aryl, or R6 and R7 together with the nitrogen to which they are attached form an optionally substituted piperazinyl, morpholinyl or piperidinyl ring;
n is 0 to 6; and
p is0 to 4.
Preferably R6 and R7 are each independently H, optionally substituted C1-10-alkyl or optionally substituted phenyl, more preferably H, optionally substituted C1-6-alkyl or optionally substituted phenyl.
When T is a group which is convertible to vinyl on treatment with aqueous alkali it is preferably of the formula xe2x80x94CH2CH2OSO3H, xe2x80x94CH2CH2SSO3H, xe2x80x94CH2CH2Cl or xe2x80x94CH2CH2OCOCH3. Preferably T is xe2x80x94NR6R7, xe2x80x94CHxe2x95x90CH2 or xe2x80x94CH2CH2OSO3H and especially xe2x80x94CHxe2x95x90CH2 or xe2x80x94NR6R7, wherein R6 and R7 are as hereinbefore defined.
Preferably each B independently is xe2x80x94COOH, xe2x80x94SO3H, xe2x80x94PO3H2, xe2x80x94CF3, optionally substituted C1-10-alkoxy, optionally substituted C1-10-alkyl, optionally substituted amino xe2x80x94SO2CHxe2x95x90CH2, xe2x80x94Cl, xe2x80x94Br, xe2x80x94I, xe2x80x94CN, xe2x80x94OH, xe2x80x94NO2 or xe2x80x94SO2NR6R7, wherein R6 and R7 are as hereinbefore defined.
Preferred optional substituents on B are selected from C1-6-alkyl, C1-6-hydroxyalkyl, C1-6-alkoxy, C1-4-alkylCO, xe2x80x94OH, xe2x80x94SO3H, xe2x80x94COOH, xe2x80x94CN, xe2x80x94PO3H2, halo and xe2x80x94NH2.
In a preferred embodiment each B independently is xe2x80x94COOH, xe2x80x94SO3H, xe2x80x94OH, xe2x80x94CF3, Cl, xe2x80x94NH2, xe2x80x94NHCOC1-4-alkyl, xe2x80x94NHC1-4-alkyl, xe2x80x94NHC1-4-hydroxyalkyl, C1-6-alkoxy xe2x80x94SO2NHC1-4-alkyl, xe2x80x94SO2NHC1-4-hydroxyalkyl or C1-6-alkyl optionally substituted by xe2x80x94OH, xe2x80x94COOH, xe2x80x94NH2 or xe2x80x94SO3H. It is especially preferred that each B independently is C1-4-alkyl, xe2x80x94COOH, xe2x80x94OH, xe2x80x94SO3H or xe2x80x94NHCOC1-4-alkyl, more especially methyl, ethyl, xe2x80x94NHCOCH3 or xe2x80x94COOH.
Preferably any substituents represented by B in Formulae (2) and (3) are located in a position other than the ortho position relative to the azo group in Formula (1).
Preferably each n independently is 0, 1 or 2, more preferably 0.
Preferably each p independently is 0, 1 or 2, more preferably 0.
In a preferred embodiment each Ar is, independently, of the Formula (3) wherein each p is 0, 1 or 2 (preferably 0) and each B is as hereinbefore defined, more preferably xe2x80x94COOH, xe2x80x94OH, xe2x80x94SO3H or xe2x80x94Cl. It is especially preferred that each Ar is 2-carboxyphenyl. For ease of synthesis it is preferred that each Ar is the same.
Preferably each R1 independently is H or optionally substituted C1-6-alkyl, more preferably H or C1-4-alkyl optionally substituted by xe2x80x94COOH, xe2x80x94SO3H, xe2x80x94CN or more preferably xe2x80x94OH. It is especially preferred that each R1 independently is H, methyl, ethyl or hydroxyethyl. It is most preferred that each R1 is H.
Preferably each X independently is xe2x80x94Sxe2x80x94 or xe2x80x94NR1xe2x80x94, more preferably xe2x80x94NR1xe2x80x94 and especially xe2x80x94NHxe2x80x94.
When R2, R3, R4 or R5 is optionally substituted alkyl it is preferably optionally substituted C1-20-alkyl, more preferably optionally substituted C1-10-alkyl and especially optionally substituted C1-6-alkyl. Preferred optional substituents include C1-6-alkoxy, C1-6-hydroxyalkoxy, xe2x80x94OH, xe2x80x94COOH, xe2x80x94SO3H, xe2x80x94PO3H2, xe2x80x94CN, a 5- or 6-membered heterocyclic group or optionally substituted amino. Preferred 5- or 6-membered heterocyclic groups are furanyl, tetrahydrofuranyl, piperazinyl and morpholinyl each of which is optionally substituted by xe2x80x94OH, xe2x80x94COOH, xe2x80x94SO3H or C1-4-alkyl.
When any of R2, R3, R4 or R5 is optionally substituted aryl it is preferably optionally substituted phenyl or naphthyl, more preferably optionally substituted phenyl. Preferred optional substituents are C1-6-alkoxy, halo (preferably F or Cl), xe2x80x94OH, xe2x80x94CN, xe2x80x94COOH, xe2x80x94SO3H, xe2x80x94PO3H2, xe2x80x94NO2, xe2x80x94NH2, xe2x80x94COC1-4-alkyl, xe2x80x94NHCOC1-4-alkyl-(C1-6-alkylene)O(C1-6-alkylene)OC1-4-alkyl,-(C2-6-alkylene)O(C2-6-alkylene)OH, xe2x80x94SO2NH2, xe2x80x94SO2NHC1-4-alkyl, C1-6-alkyl or C1-6-alkyl substituted by xe2x80x94OH, xe2x80x94COOH or xe2x80x94SO3H.
Examples of aryl groups which may be represented by any of R2, R3, R4 or R5 include 2-sulphophenyl, 2-carboxyphenyl, 4-sulphophenyl, 4-carboxyphenyl, 2-carboxy-4-suiphophenyl, 3-carboxy-2-methyl-phenyl, 4-methyl-3-sulpho-phenyl or 2,6-dimethylphenyl.
When any of R2, R3, R4 or R5 is optionally substituted aralkyl it is preferably of the formula: 
wherein
each R8 independently is C1-4-alkyl, C1-4-alkoxy, halo, xe2x80x94OH, xe2x80x94NH2, xe2x80x94COOH, xe2x80x94SO3H or xe2x80x94PO3H2; and
a is 0 to 5.
a is preferably 0, 1 or 2.
Especially preferred aralkyl groups which may be represented by R2, R3, R4 or R5 are benzyl or 2-phenylethyl, each of which is optionally substituted by xe2x80x94COOH, xe2x80x94OH or xe2x80x94SO3H.
When R4 and R5 together with the nitrogen to which they are attached form an optionally substituted 5 or 6 membered ring it is preferably an optionally substituted piperazinyl, piperidinyl or morpholinyl ring. The optional substituents on the ring are preferably selected from xe2x80x94OH, xe2x80x94COOH, xe2x80x94SO3H, C1-6-alkoxy, C1-6-alkyl and C1-6-alkyl substituted by xe2x80x94OH, xe2x80x94COOH or xe2x80x94SO3H.
When Z is a labile atom or group, it is preferably an atom or group which is displaceable by a hydroxyl group of cellulose under mildly alkaline aqueous conditions to form a covalent bond between the dye of Formula (1) and cellulose.
Preferred labile atoms and groups which may be represented by Z include halogen atoms, for example F or Cl; sulphonic acid groups; thiocyano groups; quaternary ammonium groups, for example trialkylammonium groups and optionally substituted pyridinium groups, for example 3- and 4-carboxy pyridinium groups. An especially preferred labile atom is Cl.
It is preferred, however, that each Z independently is xe2x80x94SR2, xe2x80x94OR3 or xe2x80x94NR4R5, more preferably xe2x80x94OH, xe2x80x94SR2 or xe2x80x94NR4R5 wherein R2, R4 and R5 are as hereinbefore defined. It is especially preferred that each Z independently is xe2x80x94OH, xe2x80x94SH or xe2x80x94NR9R10 wherein R9 and R10 each independently is H, C1-6-alkyl optionally substituted by xe2x80x94OH, C1-4-alkoxy, C1-4-hydroxyalkoxy, xe2x80x94COOH or xe2x80x94SO3H. Most preferably each Z independently is xe2x80x94OH, xe2x80x94SH or xe2x80x94NH2.
The floating xe2x80x94SO3H groups in Formula (1) are preferably attached at the 4- or, more preferably, the 3-position on the naphthylene groups in Formula (1) relative to the xe2x80x94NR1-group.
L preferably contains less than 20, more preferably less than 10 carbon atoms. L may contain one or more hetero atoms, for example oxygen, nitrogen or sulphur, or a combination thereof. For example, L may contain an ester, amide or xe2x80x94SSxe2x80x94 group. L may be linear or branched but is preferably linear. L may be unsaturated or, more preferably, saturated.
Preferably L is an optionally interrupted alkenylene group or more preferably an optionally interrupted alkylene group containing up to 20, more preferably up to 10 carbon atoms, said group carrying a substituent selected from xe2x80x94COOH, xe2x80x94SO3H and xe2x80x94PO3H2. When L is alkylene it is preferably optionally interrupted C2-20-, more preferably C2-10- and especially C2-6-alkylene which carries a substituent selected from xe2x80x94COOH, xe2x80x94SO3H and xe2x80x94PO3H2. When L is interrupted alkylene or alkenylene the interruption(s) is/are preferably one or more hetero atoms, preferably xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SSxe2x80x94 or xe2x80x94NR1xe2x80x94 wherein R1 is as hereinbefore defined.
It is especially preferred that L is a straight chain C2-6-alkylene group optionally interrupted by one or more xe2x80x94SSxe2x80x94 group, wherein the alkylene group carries a substituent selected from xe2x80x94COOH, xe2x80x94SO3H and -xe2x80x94PO3H2.
L may carry more than one substituent selected from xe2x80x94COOH, xe2x80x94SO3H and xe2x80x94PO3H2, or other substituents in addition those selected from xe2x80x94COOH, xe2x80x94SO3H and xe2x80x94PO3H2, for example xe2x80x94OH. However, it is preferred that the substituents on L are selected from the group consisting of xe2x80x94COOH, xe2x80x94SO3H and PO3H2. More preferably L is substituted by one or more xe2x80x94SO3H or xe2x80x94COOH group. It especially preferred that L is substituted by one or more xe2x80x94COOH group.
Examples of preferred aliphatic groups represented by L include xe2x80x94CH(COOH)CH2xe2x80x94Sxe2x80x94Sxe2x80x94CH2CH(COOH)xe2x80x94, xe2x80x94CH2CH(COOH)CH2xe2x80x94 and xe2x80x94CH2CH2CH2CH(COOH)xe2x80x94.
The compounds of Formula (1) may exist in tautomeric forms other than those shown in this specification, for example the hydrazo tautomer. These tautomers are included within the scope of the present claims.
The compounds of Formula (1) have a high solubility in aqueous media and provide bright magenta prints with a good light-fastness when incorporated into inks for ink jet printing.
In view of the foregoing preferences, preferred compounds of the Formula (1) are of Formula (4) and salts thereof: 
wherein:
L1 is a C2-20-alkylene group carrying a xe2x80x94SO3H or xe2x80x94COOH group;
each R11 independently is H or C1-4-alkyl optionally substituted by xe2x80x94OH, xe2x80x94COOH, xe2x80x94SO3H or xe2x80x94CN;
each Z1 independently is xe2x80x94SR2, xe2x80x94OR3 or xe2x80x94NR4R5; and
R2, R3, R5 and R5 are as hereinbefore defined.
The compounds of Formula (4) exhibit a particularly high aqueous solubility and when incorporated into inks suitable for use in an ink jet printer, provide prints with a high light-fastness.
Preferably each R11 independently is H or C1-4-alkyl optionally substituted by xe2x80x94OH. More preferably each R11 is H.
Preferably each Z1 independently is xe2x80x94OH, xe2x80x94SH or xe2x80x94NR9R10, wherein R9 and R10 are as hereinbefore defined.
Preferably L1 is a straight chain C2-10-, more preferably a C2-6-alkylene group which carries a one or more substituents selected from xe2x80x94COOH and xe2x80x94SO3H.
Especially preferred compounds of the Formula (4) are those wherein L1 is C2-10-alkylene carrying a xe2x80x94COOH group and each Z is xe2x80x94OH, xe2x80x94SH or xe2x80x94NR9R10 (especially xe2x80x94NH2), wherein R9 and R10are as hereinbefore defined.
The compounds according to the first aspect of the invention may be in the free acid or salt form. Preferred salts are alkali metal salts, especially lithium, sodium and potassium salts, ammonium and substituted ammonium salts. Especially preferred salts are salts with sodium, lithium, ammonia and volatile amines and mixed salts thereof, especially mixed lithium/sodium salts. The compounds may be converted into a salt using known techniques. For example, an alkali metal salt may be converted into a salt with ammonia or an amine by dissolving an alkali metal salt in water, acidifying with a mineral acid and adjusting the pH of the solution to pH 9 to 9.5 with ammonia or the amine and removing the alkali metal cations by dialysis, reverse osmosis or ultrafiltration.
The compounds of the invention may be prepared using conventional techniques for the preparation of azo dyes. For example a suitable method comprises condensing a molar excess of the compound of the formula ZH with the compound of the Formula (5): 
wherein L and each Z, Ar, R1, X and A are as hereinbefore defined.
The condensation is preferably performed in a liquid medium, more preferably an aqueous medium and especially water. Temperatures of 10xc2x0 C. to 100xc2x0 C. are preferred, more preferably from 20 to 95xc2x0 C. Preferably a reaction time of 1 to 24, more preferably 1 to 4 hours is used.
The condensation is preferably performed in the presence of a suitable base and optionally with a catalyst, for example 4-dimethylaminopyridine.
The base may be any inorganic base for example, ammonia, an alkali metal or alkali earth metal hydroxide, carbonate or bicarbonate, or an organic base. The amount of base used may be varied between wide limits but it is preferred to use less than 40, more preferably less than 10 and especially from 3 to 5 moles for each mole of the compound of Formula (5).
After the condensation reaction the product may be isolated by precipitating the product as a salt from the reaction mixture for example by the addition of a suitable alkali metal salt, especially sodium chloride. Alternatively, the product may be isolated in its free acid form by acidifying the reaction mixture, preferably using a mineral acid, especially hydrochloric acid. Where the product precipitates as a solid it may be separated from the mixture by filtration.
If desired unwanted anions may be removed from the product of the above process by dialysis, osmosis, ultrafiltration or a combination thereof.
The product of the above process may be converted, if desired, to the NH4+, quaternary ammonium or organic amine salt by the addition of ammonia, ammonium hydroxide, primary, secondary, tertiary or quaternary amine.
The compound of Formula (5) may, for example, be prepared as follows:
Stage (a): diazotising amine of the formula Ar-NH2 and coupling with the compound of the Formula 
Stage (b) hydrolysis, under alkaline conditions, to remove the acetyl group present in the product of stage (a);
Stage (c) condensing the product of stage (b) with an approximately molar equivalent of the compound of the Formula (7): 
stage(d) condensing a compound of the formula HX-L-XH with approximately 2 molar equivalents of the product of stage(c);
wherein Ar, and R1, A, L and X are as hereinbefore defined.
The diazotisation in stage (a) is preferably performed in an aqueous medium at a pH below 7 in the presence of a suitable diazotisation agent. Dilute mineral acid, e.g. HCl or H2SO4, is preferably used to achieve the desired acidic conditions. Conveniently the diazotisation agent is formed in-situ, for example by dissolving an alkali metal nitrite, preferably sodium nitrite, in a molar excess of mineral acid, preferably HCl.
The temperature of the diazotisation is not critical and may conveniently be carried out at from xe2x88x925xc2x0 C. to 20xc2x0 C., preferably from 0 to 10xc2x0 C. and especially from 0 to 5xc2x0 C.
The coupling reaction in stage (a) is preferably performed under mildly alkaline conditions, more preferably at a pH of 7-8.
The hydrolysis in stage (b) is preferably performed in aqueous NaOH at a reaction temperature of 50 to 90xc2x0 C.
The condensations in stages (c) and (d) are preferably performed in the presence of a base.
The present invention also covers mixtures comprising two or more dyes of the Formula (1). Furthermore, the dyes of Formula (1) may be mixed with commercially available dyes, especially those listed in the colour Index International, to adjust the shade or other properties as desired.
According to a second aspect of the present invention there is provided a composition comprising:
(a) one or more compound of the Formula (1) according to the first aspect of the present invention; and
(b) one or more water-soluble magenta dye other than a compound of Formula (1) according to the first aspect of the invention.
The water-soluble magenta dye is preferably a xanthene dye, an azo or bis azo dye, more preferably an anionic azo or bis azo dye and especially an azo or bis azo dye which contains one or more groups selected from sulphonate, carboxylate and thiocarboxylate groups.
Preferred water-soluble magenta dyes include C.I. Acid Red 50, 52, 87, 91, 92, 95, 249 and 289; C.I. Direct Violet 106 and 107; compounds 100 to 107, 200 and 201 described on pages 8 and 9 of WO 96/24636; compounds 1 to 24 shown described on cols. 4 to 10 in U.S. Pat. No. 5,542,970; compounds 1 to 55 described on pages 7 to 17 of EP-A-682 088; compounds 1 to 14 shown in Example 1 to 6 of EP-A-194,885; compounds 1 to 24 described on pages 8 to 13 of EP-A-717 089; the compounds described in examples 1 to 16 in cols 5 to 11 of U.S. Pat. No. 5,262,527; the dyes described in Examples 1 to 21 in WO 94/16021; and one or more dyes of the Formula (8) and salts thereof: 
wherein:
each v is independently, xe2x80x94SO3H, xe2x80x94COOH, xe2x80x94CF3, alkoxy, alkyl or xe2x80x94PO3H2;
Q is an organic linking group;
each R12 is independently, H or optionally substituted alkyl;
each A independently is N, Cxe2x80x94Cl, Cxe2x80x94CN or Cxe2x80x94NO2;
each W is independently, xe2x80x94SR13, xe2x80x94OR14, xe2x80x94NR15R16 or halogen;
R13, R14, R15 and R16 are, each independently, H, optionally substituted alkyl, optionally substituted aryl or optionally substituted aralkyl; or
R14 and R15 together with the nitrogen to which they are attached, form an optionally substituted five or six membered ring;
Especially preferred water-soluble magenta dyes for use in the composition according to the second aspect of the invention include C.I. Acid Red 52, C.I. Acid Red 289 or a dye of the Formula (9), (10) and (11) and salts thereof: 
The dye of Formula (9) may be prepared using the method described in Example 1 of EP 0 559 310. The dye of the Formula (10) may be prepared using the method described in Example 3 of PCT publication number WO 94/16021. The dye of Formula (11) may be prepared using the method described in Example 1 of WO 96/24636.
The composition according to the second aspect of the present invention preferably comprises:
(a) from 1 to 99, more preferably from 3 to 70 and especially from 5 to 50 parts in total of the compound(s) of Formula (1); and
(b) from 99 to 1, more preferably from 30 to 97 parts and especially 95 to 50 parts in total of the water-soluble magenta dye(s);
wherein the parts are by weight and the sum of the parts (a)+(b)=100.
The composition may contain a single dye of Formula (1) or a mixture of two or more dyes of the Formula (1). Similarly, the composition may contain a single water-soluble magenta dye other than a compound of Formula (1) or a mixture of two or more water-soluble magenta dyes other than compounds of Formula (1).
The compounds and compositions according to the first and second aspects of the present invention may be, and preferably are, purified to remove undesirable impurities before they are incorporated into inks for ink jet printing. Conventional techniques may be employed for purification, for example ultrafiltration, reverse osmosis and/or dialysis.
According to a third aspect of the present invention there is provided an ink comprising:
(a) a compound according to the first aspect of the present invention, or a composition according to the second aspect of the invention; and
(b) a liquid medium.
Preferably component (a) of the ink is one of the preferred compounds or compositions as hereinbefore described in relation to the first or second aspect of the invention. More preferably component (a) is one or more compounds of the Formula (1) or Formula (4), as hereinbefore defined.
The liquid medium preferably comprises:
(i) water;
(ii) a mixture of water and an organic solvent; or
(iii) an organic solvent free from water.
The number of parts by weight of component (a) of the ink is preferably from 0.01 to 30, more preferably 0.1 to 20, especially from 0.5 to 15, and more especially from 1 to 5 parts. The number of parts by weight of component (b) is preferably from 99.99 to 70, more preferably from 99.9 to 80, especially from 99.5 to 85, and more especially from 99 to 95 parts. The number of parts (a)+(b) is 100.
Preferably component (a) is completely dissolved in component (b). Preferably component (a) has a solubility in component (b) at 20xc2x0 C. of at least 10%. This allows the preparation of concentrates which may be used to prepare more dilute inks and reduces the chance of the compound(s) of component (a) of the ink precipitating if evaporation of the liquid medium occurs during storage.
When the liquid medium comprises a mixture of water and an organic solvent, the weight ratio of water to organic solvent is preferably from 99:1 to 1:99, more preferably from 99:1 to 50:50 and especially from 95:5 to 80:20.
It is preferred that the organic solvent present in the mixture of water and organic solvent is a water-miscible organic solvent or a mixture of such solvents. Preferred water-miscible organic solvents include C1-6-alkanols, preferably methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol and cyclohexanol; linear amides, preferably dimethylformamide or dimethylacetamide; ketones and ketone-alcohols, preferably acetone, methyl ether ketone, cyclohexanone and diacetone alcohol; water-miscible ethers, preferably tetrahydrofuran and dioxane; diols, preferably diols having from 2 to 12 carbon atoms, for example pentane-1,5-diol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol and thiodiglycol and oligo- and poly-alkyleneglycols, preferably diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol; triols, preferably glycerol and 1,2,6-hexanetriol; mono-C1-4-alkyl ethers of diols, preferably mono-C1-4-alkyl ethers of diols having 2 to 12 carbon atoms, especially 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol, 2-[2-(2-methoxyethoxy)ethoxy]ethanol, 2-[2-(2-ethoxyethoxy)-ethoxy]-ethanol and ethyleneglycol monoallylether; cyclic amides, preferably 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, caprolactam and is 1,3-dimethylimidazolidone; cyclic esters, preferably caprolactone; sulphoxides, preferably dimethyl sulphoxide and sulpholane. Preferably the liquid medium comprises water and 2 or more, especially from 2 to 8, water-miscible organic solvents.
Examples of further suitable ink media comprising a mixture of water and one or more organic solvents are described in U.S. Pat. No. 4,963,189, U.S. Pat. No. 4,703,113, U.S. Pat. No. 4,626,284, EP 425,150A and U.S. Pat. No. 5,207,824.
When the liquid medium comprises an organic solvent free from water, (i.e. less than 1% water by weight) the solvent preferably has a boiling point of from 30xc2x0 to 200xc2x0 C., more preferably of from 40xc2x0 to 150xc2x0 C., especially from 50 to 125xc2x0 C. The organic solvent may be water-immiscible, water-miscible or a mixture of such solvents. Preferred water-miscible organic solvents are any of the hereinbefore described water-miscible organic solvents and mixtures thereof. Preferred water-immiscible solvents include, for example, aliphatic hydrocarbons; esters, preferably ethyl acetate; chlorinated hydrocarbons, preferably CH2Cl2; and ethers, preferably diethyl ether; and mixtures thereof.
When the liquid medium comprises a water-immiscible organic solvent, preferably a polar solvent is included because this enhances solubility of the dye in the liquid medium. Examples of polar solvents include C1-4-alcohols. In view of the foregoing preferences it is especially preferred that where the liquid medium is an organic solvent free from water it comprises a ketone (especially methyl ethyl ketone) and/or an alcohol (especially a C1-4-alkanol, such as ethanol or propanol).
The organic solvent free from water may be a single organic solvent or a mixture of two or more organic solvents. It is preferred that when the medium is an organic solvent free from water it is a mixture of 2 to 5 different organic solvents. This allows a medium to be selected which gives good control over the drying characteristics and storage stability of the ink.
Ink media comprising an organic solvent free from water are particularly useful where fast drying times are required and particularly when printing onto hydrophobic and non-absorbent substrates, for example plastics, metal and glass.
An especially preferred ink comprises:
(a) from 1 to 10 parts in total of a compound or composition according to the first or second aspect of the invention;
(b) from 2 to 60, more preferably 5 to 40 parts of water-soluble organic solvent; and
(c) from 30 to 97, more preferably 40 to 85 parts water; wherein all parts are by weight and the sum of the parts (a)+(b)+(c)=100.
The ink may also contain additional components conventionally used in ink jet printing inks, for example viscosity and surface tension modifiers, corrosion inhibitors, biocides, kogation reducing additives, anti-cockle agents to reduce paper curling and surfactants which may be ionic or non-ionic.
The pH of the ink is preferably from 4 to 10.
When the ink according to the third aspect of the invention is used as an ink jet printing ink, the ink preferably has a concentration of less than 100 parts per million, more preferably less than 50 parts per million, in total of halide ions and divalent and trivalent metals. This reduces nozzle blockage in ink jet printing heads, particularly in thermal ink jet printers. The inks may be purified using conventional techniques, for example ultrafiltrating reverse osmosis, dialysis or a combination thereof.
A fourth aspect of the present invention provides a process for printing an image on a substrate comprising applying thereto by means of an ink jet printer an ink containing a compound according to the first aspect of the invention or a composition according to the second aspect of the invention.
The ink used in this process is preferably as defined in the third aspect of the present invention
The ink jet printer preferably applies the ink to the substrate in the form of droplets which are ejected through a small orifice onto the substrate. Preferred ink jet printers are piezoelectric ink jet printers and thermal ink jet printers. In thermal ink jet printers, programmed pulses of heat are applied to the ink in a reservoir by means of a resistor adjacent to the orifice, thereby causing the ink to be ejected in the form of small droplets directed towards the substrate during relative movement between the substrate and the orifice. In piezoelectric ink jet printers the oscillation of a small crystal causes ejection of the ink from the orifice.
The substrate is preferably paper, plastic, a textile, metal or glass, more preferably paper, an overhead projector slide or a textile material, especially paper.
Preferred papers are plain or treated papers which may have an acid, alkaline or neutral character. Examples of commercially available papers include, HP Premium Coated Paper, HP Photopaper (all available from Hewlett Packard Inc.), Stylus Pro 720 dpi Coated Paper, Epson Photo Quality Glossy Film, Epson Photo Quality Glossy Paper (available from Seiko Epson Corp.), Canon HR 101 High Resolution Paper, Canon GP 201 Glossy Paper, Canon HG 101 High Gloss Film (all available from Canon Inc.), Wiggins Conqueror paper (available from Wiggins Teape Ltd), Xerox Acid Paper and Xerox Alkaline paper, Xerox Acid Paper (available from Xerox).
A fifth aspect of the present invention provides a substrate, preferably a paper, an overhead projector slide or a textile material, printed with an ink according to the third aspect of the present invention or by means of the process according to the fourth aspect of the present invention.
According to a sixth aspect of the present invention there is provided an ink jet printer cartridge comprising a chamber and ink, wherein the ink is present in the chamber and the ink contains a compound or a composition according to the second or third aspect of the invention. Preferably the ink is an ink according to the third aspect of the invention.
According to an eighth aspect of the present invention there is provided an ink jet printer containing an ink jet printer cartridge, wherein the ink jet printer cartridge is as defined in the seventh aspect of the present invention.